1. Field
Embodiments of the present invention relate to a hydraulic unit, and more particularly, to a hydraulic unit of an electronic control brake system for adjusting brake pressure in the electronic control brake system through electronic control.
2. Description of the Related Art
Electronic control brake systems are used to effectively prevent a slipping phenomenon that may occur during a brake operation, sudden unintended acceleration, or a burst of speed of a vehicle. An electronic control brake system generally includes a booster device, a master cylinder, and a wheel cylinder of a brake system for a vehicle, a hydraulic unit for adjusting brake hydraulic pressure, and an electronic control unit for controlling the hydraulic unit.
The hydraulic unit includes a plurality of solenoid valves (introduction/discharge valves) for controlling brake hydraulic pressure transmitted to the wheel cylinder disposed at each wheel, a low-pressure accumulator for temporarily storing oil discharged from the wheel cylinder, a pair of pumps driven by a motor, and a shuttle valve and a driving force controlling valve that are disposed at a suction side and a discharge side of each of the pair of pumps, respectively. These components are built in a modulator block formed of aluminum (Al).
Also, in the modulator block of the hydraulic unit, a high-pressure accumulator is mounted on the discharge side of the pump so as to reduce pressure pulsation of the oil that is pressed and discharged by operations of the pumps.
In order to compactly install a plurality of components in the modulator block, ports for connecting a plurality of valve bores, pump bores, motor accommodation bores, accumulator bores, the master cylinder, and the wheel cylinder, and a plurality of flow paths that suggest a direction of a flow of the hydraulic pressure are processed.
However, an unused space except for a space in which a plurality of components are disposed, unnecessarily exists in a hydraulic unit according to the related art such that improvements in the arrangement structure of the components are required. In particular, when a high-pressure accumulator is installed in the modulator block, the modulator block is disposed while its size is increased, such that the size and weight of the hydraulic unit are increased and thus cost increases. The hydraulic unit having the high-pressure accumulator installed therein is disposed in Germany Patent No. 10-2008-037047.
The high-pressure accumulator installed in the hydraulic unit according to the related art is disposed at an upper side of a hydraulic pump to be parallel to the hydraulic pump so as to be directly connected to the hydraulic pump through one flow path, and an orifice is formed in bores of the high-pressure accumulator. The flow path that connects the high-pressure accumulator and the hydraulic pump is slantly formed in a diagonal direction. This is because there is a spatial limitation in the modulator block in forming general brake flow paths due to a problem of parallel arrangement of the high-pressure accumulator and the hydraulic pump and the position of the orifice formed in the bores of the high-pressure accumulator. That is, since general brake flow path and anti-lock braking system (ABS) flow path cannot be used in the same manner, flow paths are formed in the diagonal direction due to the spatial limitation in the modulator block while general brake flow paths and ABS flow paths are dualized. In this way, as the flow paths are slantly formed in the diagonal direction, it is difficult to perform processing of the flow paths compared to straight flow paths.